Studies on patients with systemic lupus erythematosus are underway to study the presence and significance of viral antibodies and the response of their lymphocytes to viral antigen stimulation. Studies of the patients and matched controls from the same geographic area revealed no difference in incidence of transplantation antigens of the HL-A series in 48 patients and controls. Analysis of the data on these 48 patients and 48 controls for relationship of HL-A antigen and viral antibody response has thus far shown no significance. Throat cultures for EB virus has been positive in a small number of lupus patients tested (3 of 6 whereas none of 3 controls were positive). The controls were obtained from individuals attending the same clinic as the SLE patients and studies of the cultures were done blind. Preliminary results on the viral stimulation of lymphocytes revealed significant depression of response of SLE lymphocytes compared to controls, using rubella, measles, Para 1 and EBV. However, the numbers of patients tested thus far is small.